Has anybody else had past data change in PBCS?

Summary

Actausl from prior years appear to ahve changed in PBCS several timese in the last few eeks, appropos of no known action on our part

Content

We keep several years worth of actuals in our PBCS system so that they're available for budget managers to look at alongside the next year budget as they're developing it. These were uploaded a while ago and don't change (since they're actuals for closed years, going back to 2012). In January, we've had several incidents where these historical actual totals seem to have changed. We don't exactly when this occurring- we only discover it when somebody notices that one of the numbers in one of the reports looks a little odd. I have not been able to correlate this to